Electrical regulating system



Sept. 24, 1946. R c. OLESEN v ELECTRICAL REGULATING SYSTEM 1 Filed May 19, 1 944 mid m J l 4 f w mm I INVENTOR @ym0d 63 01cm BY M ATTOR EYS Patented Sept. 24, 1946 ELECTRICAL REGULATING SYSTEM Raymond C. Olesen, Altadena, Calif., assignor to Consolidated Engineering Corporation, Pasadena, Calif., a corporation of California Application May 19, 1944, Serial No. 536,379

This invention relates to electrical regulating systems and has for its object to maintain a constant current orvoltage in an electrical cirouit.

wherein it is desired to maintain a constant current flow or constant voltage across anelement in spite of variations introduced for example,

by irregular supply voltage or irregularities of the cathode or anode circuits of a vacuum tube. In particular, it is desirable in many instances to maintain a constant anode current in avacuum tube.

According to my invention I maintain a constant anode current in a vacuum tube circuit controlling the filament currentof the tube in accordance with the anode current.

A feature of my invention is the provision of a self-balancing bridge having, an arm whose impedance is varied in accordance with the current which is to be maintained constant. The output of the bridge is used to control the current through the tube. 1

The above and other features will be better understood from the followingdetailed descrip tion and the accompanying drawing which shows a system embodying my invention.

In the drawing, V1 represents a vacuum tube having a filament type cathode l and an anode 2, with a load 3 connected in the anode circuit between the anode and ground. The load may be of any desired type, for example, a resistance across which a voltage may be taken to be used elsewhere. Or in some cases, for example, where the tube V1 is used in gas analysis work, the load 3 may be omitted. Current for heating the filament l is supplied from an alternating voltage source t2, which is applied on the primary All of a transformerTs, the secondary winding 39 of. which has its terminals connected respectively to the outer terminals of the respective primary coils i -and of transformerTL V2. These are of the three-element type having a cathode, an anode and a control electrode. The cathodes are connected together and to the grounded midpoint of secondary winding 39. The current flowing through windings 4 and 5 is the anode current through the respective control tubes V3 and V2. The alternating voltage at seoondarywinding 6 of transformer T1 is brought to a suitable rectifier 1 from which the rectified power is supplied to the filament l of tube V1 in a conventional manner through. a ripple- There are many types of electrical circuits The circuits of primary windings 4 and 5 are come plcted through respective vacuum tubes V and' (iClaims. (Cl. 315101) 9, and shunt condensers 44 and H.

removing filter comprising series chokes 8 and There is connected across the filament a resistance it] having its midpoint connected to ground. When the filament is heatcd,'a uni-directional current flows between the anode and cathode of tube V1 and through its anode circuit to ground, by operation of the anode voltage source 45.

It is desired to maintain the anode current of tube V; constant. Ordinarily some variations would be superimposed on the otherwise steady anode current, due to such influence as uneven cathode emission or irregularities in the voltage supplied through the transformer T1 or by voltage source l-E. These irregularities are overcome and the anode current is maintained constant in spite of them by operation of the following apparatus:

There is included in series with the anode circuit of tube V1 a coil l2 wound on the middle leg of a three-legged reactor core 13. On the outer two legs of the core are respectively windings l4 and is connected in series aiding relation and constituting one arm of a four-arm bridge IS. The other three arms of the bridge comprise respectively resistor H, the parallel connected condenser I8 and resistor Hi, and the resistor Zil. The reactor core I3 is the saturable type with enough current flowing through windings I and I5 to keep it at a point of saturation. Changes of the direct current through coil I! thus produce corresponding changes of the reactance of coils l4 and I5, an increase of current through It causing a, decrease of impedance of it l5, and vice versa.

An alternating voltage from an alternating voltage source 2| having the same frequency as source 42, is impressed through transformer T2 across the opposite bridge terminals 22 and 23 which constitute the input terminals of the bridge. The remaining conjugate pair of terminals 24 and 25 are the output terminals and are connected to the input terminals 26 and 21 of amplifier 28, the terminal 21 being grounded.

.The output terminals of the amplifier, 29 and 39 are connected to the primary coil ill of a transformer T3, through a switch S1. Transformer T3 has "two secondary windings 32 and 33. The adjacent terminals of windings'32 and 33 are connected respectively to the opposite'terminals of the secondary winding 34 of a transformer T4, the midpoint of which is grounded. The remaining two terminals of windings 32 and 33 are connected through resistors 35 and36 3 respectively to the control grids 31 and 38 of three-electrode vacuum tubes V2 and V3.

Alternating voltage is impressed on the primary windings 40 and 4! of transformers T4 and T5 by the alternating voltage source 42. There is connected across source 42 a potentiometer 43 between the adjustable tap and fixed terminal of which primary winding 43 is connected to permit adjustment of the voltage on winding 2-0.

In operation, the power for heating filament l of tube V1 is supplied from alternating voltage source 42 through transformers T5 and T1 and the rectifier I. The voltage output of transformer T1 to the rectifier I is governed by the current which can pass between the anode and cathode of the respective control tubes V2 and V3. This current through the control tubes is in turn governed by the alternating voltage on their control grids 38 and 31. When switch S1 is open the voltage on the grids 3'! and 38 is an alternating voltage of the same frequency as the voltage on the anodes of the same tubes; and this alternating voltage on the grids establishes a definite amount of current flow in transformer T1.

With switch S1 closed, the voltage on the control grids 31 and 38 is changed in accordance with any voltage output from the bridge I6, and the effect is to vary the voltage on the control grids in accordance with the anode current of tube V1. Assume, for example, that the anode current of tube V1 tends to increase causing increased current to flow through coil l2 of the saturable core reactor. This would increase the reluctance of the core and decrease the inductance of coils M and I5. This would tend to unbalance the normally balanced bridge and cause an alternating current input voltage from source 2| to be applied to the input terminals 26 and 21 of amplifier 28 and thereby cause current to flow in the primary coil 3| of transformer T3 (switch S1 being closed). This will induce in secondary coils 32 and 33 a voltage which is superimposed on the voltage normally in those coils, derived from source 42, and is of a polarity to make the alternating voltage on grids 31 and 38 more in opposition to the anode voltages of these tubes, so that less current will flow through windings 4 and 5 of transformer T1. corresponding decrease in current supplied to the filament cathode I, and will reduce the filament emission and tend to keep the anode current of tube V1 down to its normal original value.

Any tendency toward reduction of the anode current of tube V1 will similarly operate through the bridge to produce a corresponding increase of the current through filament i to counteract the decrease of the anode current.

Accordingly the anode current tends to maintain its normal steady value in spite of fluctuations due to extraneous causes and the bridge [6 acts as a self-balancing bridge to bring this about.

I claim:

1. A system for maintaining a constant anode current through a vacuum tube having an anode and a. cathode which when heated emits electrons, said system comprising a rectifier for'supplying current for heating said cathode, a source of alternating voltage for supplying power to said rec 'fier, controlled regulating means for regulating the voltage from said source to the rectifier, a bridge having a pair of opposite input ter- This wil1 result in a 1 normally maintained in balance with no output voltage at the output terminals, one of said bridge arms comprising a variable impedance element, means orrelated with the impedance element and the anode circuit for producing a variation of the impedance of said impedance element in correspondence with variation of the anode current, thereby producing a corresponding unbalance and output voltage at the bridge output terminals, and means for applying to the regulating means a control voltage derived from the bridge output in the polarity which tends to decrease the voltage to the rectifier when the anode current tends to increase, and to increase the voltage to the rectifier when the anode current tends to decrease. whereby the anode current is maintained substantially constant.

2. A system for maintaining a constant anode current through a vacuum tube having an anode and. a cathode which when heated emits electrons, said system comprising a rectifier circuit for supplying current for heating said cathode, a source of alternating voltage for supplying power to said rectifier, a voltage controlled regulating means for regulating the voltage supplied from said source to the rectifier, a saturable core minals and a conjugate pair of opposite output reactor having a winding in the anode circuit, a four-arm bridge having a pair of opposite input terminals and a conjugate pair of opposite output terminals and a second winding of said reactor in one of its arms, a source of alternating voltage connected to the input terminals, said bridge being normally maintained in balance with no output voltage at its output terminals and means for applying to the regulating means a control voltage derived from the bridge output in the polarity which tends to decrease the voltage to the rectifier when the anode current tends to increase and to increase the voltage to the rectifier when the anode current tends to decrease, whereby the anode current is maintained substantially constant.

A system for maintaining a constant anode current through a vacuum tube having an anode and a cathode whichwhen heated emits electrons, said system comprising a rectifier for supplying current for heating said cathode, a source of alternating voltage for supplying power to said rectifier, a control tube having a cathode, anode and control electrode for regulating the power supply to the rectifier, a second source of alternating voltage of the same frequency as the firstmentioned source and connected .to said control electrode in phase opposition to the voltage on the anode of said control tube, and means for varying the voltage of said second source, said means comprising a normally balanced bridge having four impedance arms and a pair of opposite input terminals and a conjugate pair of opposite output terminals, a third source of alternating voltage of said frequency applied to the input terminals of said bridge, a saturable reactor having a saturable core and a plurality of windings on the core, a first of said windings being in the anode circuit of said vacuum tube, and a second of said windings being in one of said bridge arms whereby the bridge becomes unbalanced by changes of rt-he current through said first winding, and connections from the output terminals of the bridge for changing the magnitude of the voltage of said second source in accordance with the degree of bridge unbalance, the changes being in the direction which decreases the cathode heating current when said anode current increases, and increases the oathode heating current when said anode current decreases, whereby the anode current is maintained substantially constant.

l. Apparatus according to claim 3, in which said saturable core of the reactor has three legs, and said first winding is on one of the legs and the second winding comprises two coils, one coil being on each of the other two legs, said two coils being arranged in the series-aiding connection.

5. A system for maintaining a constant anode current through a Vacuum tube having an anode and a cathode which when heated emits electrons, said system comprising a rectifier for supplying current for heating said cathode, a first source of alternating voltage for supplying said rectifier,

' a pair of control tubes each having a cathode, an

ance arms with a pair of opposite input terminals and a, conjugate pair of opposite output terminals, a third source of alternating voltage of the same frequency connected to said input terminals, one of said impedance arms comprising a variable impedance element, means correlated with the variable impedance element and the anode circuit for producing a variation of the impedance of said variable impedance element in correspondence with variation of the anode current, whereby changes of said anode-current produce corresponding unb-alances of the bridge and control means responsive to the bridge output which applies control voltages to the respective control electrodes in the polarity which changes said cathode heating current in the direction opposite to changes of said anode current, whereby the anode current is maintained substantially constant.

6. Apparatus according to claim 5 in which the control means comprises a transformer having a primary winding which receives voltage from the output of-said bridge and a pair of secondary windings each of which is connected to a separate one of said control electrodes.

RAYMOND c. OLESEN. 

